code: def get_backend(scheme: str) -> Backend:
      """
      Get the Backend instance for the given *scheme*.
      It looks for matching scheme in dask's internal cache, and falls-back to
      package metadata for the group name ``distributed.comm.backends``
      """
  
      backend = backends.get(scheme)
      if backend is not None:
          return backend
  
      for backend_class_ep in _entry_points(
          name=scheme, group="distributed.comm.backends"
      ):
          backend = backend_class_ep.load()()
          backends[scheme] = backend
          return backend
  
      raise ValueError(
          f"unknown address scheme {scheme!r} (known schemes: {sorted(backends)})"
      )
  
file_path: distributed/distributed/comm/registry.py
imports: from __future__ import annotations
  import importlib.metadata
  import sys
  from abc import ABC, abstractmethod
  from collections.abc import Iterable
  from typing import Protocol
label_desc: Use image node_id 1 for calling a global function with example usage: get_backend(scheme) and returns: backend, backend